1. Field of the Invention
The present invention relates to a fuel interception valve which is installed to the upper opening portion of a fuel tank, wherein at the normal state, the valve is opened and a draft state is maintained, and at the liquid level rising state and at the vehicle falling down sideways, the valve is closed and the fuel is prevented from flowing away.
2. Description of the Prior Art
Such a fuel interception valve is disclosed, for example, in that shown in FIG. 1 (refer to Japanese utility model application laid-open No. 62-87274).
This is a fuel vapor valve which is installed on the upper surface of a fuel tank 1 and comprises a body 2 of resin provided at the inside with a draft hole 3, a valve chest 4 and a valve hole 5 to perform communication between both parts 3 and 4; and a float 6 of resin which is loosely inserted in the valve chest 4 and openes or closes the valve hole 5 with a tip end portion 9 projecting at its upper surface, and a coil spring 7 which pushes up and urges the float 6 towards the valve hole 5 by load less than the self weight of the float 6.
Function of the valve is as follows:
The float 6 is moved downward by the self weight larger than the load of the coil spring 7 and opens the valve hole 5 and functions as a breather within the fuel tank 1, and on the other hand, the liquid level of the liquid fuel G rises, the float 6 rises by the buoyancy and the load of the coil spring 7 and the tip end portion 9 is closely contacted with the tapered inner surface 8 of the valve hole 5, and the float 6 is made of resin as starting material having specific gravity larger than that of the fuel liquid G, and at the vehicle falling down sideways the valve hole 5 is closed thereby the valve has functions as a roll over valve.
However, in the coil spring used in the fuel interception valve of the above-mentioned specification the strict load tolerance is required from the viewpoint of the functions.
When the float 6 comes to the valve close position due to the liquid surface rising and then the liquid surface falls, if the inner pressure is high and the difference between the inner pressure and the outer pressure is large, the float 6 sticks to the valve hole and the valve opening response property is not good. This tendency is noticeable when the breather function of large capacity is required and diameter of the valve hole is large.